New Face in Human Family Tree

A nine-year-old South African boy out with his scientist father discovered the first known fossils of a pre-human species that has experts arguing anew over the roots of mankind's family tree.

The bones belong to an adult female and teenage male who apparently fell to their death down a deep cave shaft near Johannesburg between 1.78 million and 1.95 million years ago, a time when four or more ape-like hominid species existed in Africa and the founding human line had already begun taking shape. The remains may represent an evolutionary dead end—or the first hint of a new beginning.

ENLARGE

Head of prehuman species, Australopithecus sediba, was found in 2008.
Associated Press

Matthew Berger first noticed the fossils in March 2008 during a field trip to the unexplored Malapa caves with his father, paleoanthropologist Lee Berger of the University of the Witwatersrand, who then led 60 scientists in analyzing and identifying the new species. They named it Australopithecus sediba, after the word for "well-spring" in the local Sesotho language.

"Matthew ran off the site and within about a minute and a half said, 'Dad, I found a fossil,' " Dr. Berger said. "I realized he had a hominid clavicle. He did indeed make the first discovery."

The collection of 130 bones was made public Thursday at a news conference at the United Nations' Cradle of Humankind World Heritage Site, which encompasses the cave site near Johannesburg, and was detailed in research papers published in the journal Science.

The team is excavating at least two other skeletons there belonging to the same species, which they wouldn't discuss.

"I think he [Dr. Berger] is on to a gold mine," said paleoanthropologist Ian Tattersall, curator at the American Museum of Natural History in New York, who wasn't involved in the find.

Taken together, the partial skeletons made public so far combine primitive characteristics of the burly, small-brained predecessors to the human family, known generally as Australopithecines, and advanced features more typical of the modern genus Homo, the broad family classification that encompasses the direct ancestors of modern humankind.

A 9-year-old boy has discovered the first known fossils of a primitive pre-human species in South Africa, a finding that has scientists arguing anew over the roots of the human family tree. Science Columnist Robert Lee Hotz has the details of the new discovery in an interview with Simon Constable.

The bones may require scientists to revise the history of human evolution again. Fossil finds in Africa, Asia and the Middle East in recent decades have turned the story of human development from a straightforward saga of evolutionary progress, in which species one-by-one led directly to the next more advanced form, into a more confusing family drama that featured many pre-human species living simultaneously.

So far, there are few clues about which of those, such as the Neanderthals, simply died out leaving no descendants, which were only distantly related cousins, and which became the most direct ancestors of modern homo sapiens, as contemporary humankind is known.

"This [newest find] is a thing that has a unique relationship to us," said paleoanthropologist William Kimbel at Arizona State University's Institute of Human Origins. "They are extraordinarily important."

These newly discovered creatures were a mosaic of evolution's experiments in human biology. They easily walked upright but still took refuge in trees, the evidence suggests, and were tall for the era but still squat, measuring about four feet, four inches tall. The specimens had an almost human face, with dainty teeth and a protruding nose, but a tiny brain, and strode on lanky legs with primitive feet.

They also had gangling arms as long as an orangutan's but relatively modern hands. So far, there is no evidence these creatures used tools.

"They make a very good candidate ancestor," Dr. Berger said.

By the available evidence, though, the group to which the modern human family belongs—the genus Homo—was already widespread in Africa and parts of East Asia before the Sediba creatures lived. The scientists acknowledged that the specimens they unearthed had lived too recently to be the ancestors of the more advanced groups with whom they coexisted, but speculated that there may be older examples of the species awaiting discovery.

Straddling scientific classifications, the find has sharply divided researchers who study the human pedigree. They acclaimed the find's importance, but questioned its significance.

"Evolution is wonderfully messy," said paleoanthropologist Richard Potts, director of the Smithsonian Institution's Human Origins program, and such technical disputes are the norm.

Anthropologist Donald Johanson at Arizona State, who discovered the 3.2-million-year-old "Lucy" skeleton from a more primitive species called australopithecus afarensis that has come to symbolize human evolution, considered the new species a parallel offshoot of the human line rather than a direct human ancestor. "I would not be surprised if the Malapa material represents a newly recognized species of Homo," Dr. Johanson said.

A Crowded Field

Paleoanthropologist Tim White at the University of California, Berkeley, whose team found "Ardi," the oldest known fossil skeleton of a human ancestor, was skeptical of any direct human connection, partly because the newly identified species coexisted with other more advanced hominid groups.

"It doesn't reveal the means by which our genus arose. It does not reveal the earliest members of our genus," Dr. White said.

Some of the creature's most human traits may be misleading clues, said anthropologist Bernard Wood at George Washington University. "This sort of face may have evolved more than once," he said. "I think these fossils are evidence that the tree of human evolutionary history had lots of twigs, all but one of which became extinct."

All in all, there aren't yet enough fossils of the species to draw conclusions, Dr. Wood said. "It is like grabbing two people off the New York subway and trying to reconstruct all of North American humanity."

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